The present invention relates to thermostatic switches and relates more particularly to a thermostatic switch which is easy to assemble, inexpensive to manufacture and, suitable for mass production.
Thermostatic switch has been commonly used in a variety of electric home appliances, for examples: electric stoves, microwave ovens, electric air-pot, and etc., for regulating temperature. It automatically controls an electric heating unit to start or stop heating at a certain temperature. FIG. 4 illustrates a thermostatic switch according to the prior art, which comprises a casing covered with a cap for holding two conductors, two contact plates and a connecting plate, which cover has a center hole with a ceramic rod movably fastened therein and covered by a bimetal element and a top cover. The bimetal element projects upwards or inwards according to temperature change so as to control the two contact plates to form into a closed or opened circuit through the two conductors and the connecting plate. This conventional structure of thermostatic switch is not satisfactory in use because of the following disadvantages.
1. It is consisted of a number of parts which are difficult to assemble;
2. Because of complicated manufacturing procedure, the manufacturing cost is high;
3. Because of complicated manufacturing and assembling procedure, any error during processing will greatly affect the quality of the product, and therefore, permanent quality is difficult to control; and
4. The insulative casing may be damaged easily during welding process to connect the conductors to the contact plate or connecting plate.